1. Field of the invention
The invention is directed to stacking systems, and more particularly a system for stacking a variety of large and heavy objects, such as steel coils upon each other.
2. Background Art
The stacking of articles has long been known in the art. Often, for transportation, a first article is positioned on a pallet. Subsequently, additional articles are stacked on top of the first article. Once the articles have been stacked, the stack of articles is fastened together, through bands, chains, tape and the like.
Such a practice has long been done with heavy steel coils. These coils often weigh hundreds, and even thousands of pounds each. As such, they are difficult to move and maneuver. In the past, certain methods have been developed to facilitate the stacking of these rolled sheets. One method has been the use of two grabbing cranes rotatably mounted about a common center, and about 180.degree. apart. The supply conveyor is positioned at one end and the destination stack is positioned 180.degree. from the supply, and abut the common center of the cranes. In operation, the first crane picks the first coil. Subsequently, the cranes rotate one half turn, thereby positioning the first crane and the coil proximate the destination stack, and the second crane proximate the supply conveyor. Accordingly, as the first crane releases the coil on the destination stack, the second crane picks up a second coil. The cranes again rotate one half turn, and the procedure is repeated until the stack is completed. Such a procedure is time consuming and extremely labor intensive. Additionally, such a procedure requires a substantial amount of space inasmuch as the the cranes require substantial room to maneuver. Moreover, the physics of starting and stopping the cranes over the appropriate areas are complicated due to the large moments of inertia caused by rotating large and heavy articles such as steel coils.